It is known that the doors of electric household appliances in which a washing cycle is performed, in particular those of front-loading washing machines, are in use blocked in a closed position by a blocking device provided with a safety device which is released only at the end of the washing cycle and, thus, when the electric household appliance is internally free from water.
The known safety devices, e.g. from U.S. Pat. No. 6,334,637, include a blocking pawl and control means for selectively moving the pawl between an extracted position and a retracted position in a through seat of a casing carrying the control means and the pawl itself therein, so that one end of the pawl, which protrudes in the extracted position from the seat may cooperate in use with a plate of the blocking device of the door, slidingly carried by a support on which the casing of the safety device is snappingly fixable; the support is in turn fixable in use to a housing of the electric household appliance, by the side of the door to be blocked and so that the sliding plate is adapted to cooperate in use, in turn, with a striker of the door.
The control devices include, in turn, a first electric actuating device, e.g. a bimetallic foil associated to a thermistor adapted to displace the pawl between the extracted and retracted position, when the electric household appliance is running, and electromagnetic blocking means of the pawl in the extracted position, in which it engages a perforation of the sliding plate, thus blocking the transversal sliding thereof on the support and, consequently, preventing the same from being released from the striker even if the user attempts to force the door into the opening position.
The electromagnetic means include, in turn, an electromagnetic actuator of the linear type which is actuated in use by means of a series of single electric pulses as a consequence of which the core of the electromagnet rotationally actuates, by means of a ratchet, a toothed wheel associated to cam means which selectively block/release the pawl in the extracted position, thus cooperating with a side appendix thereof. In this manner, by means of an appropriate shaping of the cam means and of the toothed wheel associated thereto, it is possible to obtain the blocking of the pawl and, consequently, of the entire blocking device, by applying a single electric pulse to the electromagnetic actuator, while two consecutive electric pulses are needed to release the same.
The known device described above is complex and expensive, as well as cumbersome.